Impact of invasive aquatic macrophytes on the population and behavioral ecology of mosquitoes (Diptera: Culicidae)

Authors: Turnipseed, Rakim; Moran, Patrick; Allan, Sandra - Sandy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2016
Publication Date: 3/2/2016
Citation: Turnipseed, R.K., Moran, P.J., Allan, S.A. 2016. Impact of invasive aquatic macrophytes on the population and behavioral ecology of mosquitoes (Diptera: Culicidae). Meeting Abstract. 84th Mosquito and Vector Control Association of California annual conference, Sacramento, CA February 28-March 2, 2016.

Interpretive Summary:

Technical Abstract: A field survey, three outdoor cage enclosure experiments, and laboratory studies were conducted to elucidate the impact of the invasive aquatic weeds Eichhornia crassipes (floating water hyacinth), Ludwigia hexapetala (emergent water yellow-primrose), and Egeria densa (submersed Brazilian waterweed) on the population, behavioral, and physiological ecology of Culex pipiens. This mosquito is a primary vector for West Nile Virus (WNV), and both +WNV mosquito incidence and human cases have increased over the past decade in agricultural and urban regions of the Sacramento-San Joaquin Delta, a period during which weed abundance has also increased. In a two-year field survey, C. pipiens larval abundance was higher among E. crassipes mats in closed water bodies than in open, flowing sloughs. In outdoor mesocosms containing larval C. pipiens and mosquitofish (Gambusia affinis), mosquito survival was significantly higher (by 1 to 18 percent) in mesocosms containing high densities of the three plant species than open water. At intermediate plant densities, mosquito survival was 7 percent higher among water hyacinth than either Brazilian waterweed or water primrose. At low plant densities, mosquito survival among water hyacinth was 5 and 6 percent higher than in Brazilian waterweed and open water, respectively. Thus, in some cases water hyacinth provided more protection for C. pipiens against mosquitofish than Brazilian waterweed and water primrose. In separate mesocosms in the absence of predators, C. pipiens larval development time was completed more rapidly (by at least one day) in the presence of intermediate densities of water hyacinth than with other densities of this weed, or in the presence of the other two weeds. In an outdoor adult mosquito choice experiment, females laid 34 % more eggs in mesocosms containing intermediate densities of water hyacinth than with intermediate densities of water primrose, and 99 to 100 % more eggs than in mesocosms subject to all other treatments. Laboratory choice tests in cages and an olfactometer experiment revealed that Culex pipiens laid more egg rafts and eggs on open water that had contained water hyacinth for 48 hours, than on water pre-treated with other invasive aquatic plant species. The results indicate that water hyacinth is conducive for C. pipiens mosquito reproduction and larval survival. Effective management of invasive water hyacinth in Delta waterways may thus reduce C. pipiens populations and thus human health risk.